Common OB Medications Flashcards
Pitocin (Oxytocin)
uses
induction of labor
control postpartum uterine bleeding
after Suction D&C
Pitocin (Oxytocin)
direct & indirect action
Indirect: increases intracellular Ca
direct: stimulates oxytocin receptor on the myometrium
~antidiuretic
Pitocin (Oxytocin)
contraind
fetal distress
unfavorable fetal positions
previous uterine rupture
Pitocin (Oxytocin) systemic
effects
flushing
brady/tachycardia
hyper/Hypotension
Pitocin (Oxytocin)
dose
Dose: 10-40 U in 1000cc LR
Post Csxn: keep uterus tight/small to prevent bleeding (KVO ~100ml/h)
Pitocin (Oxytocin)
onset & duration
onset: immediate
duration: within 1 hour
Pitocin (Oxytocin)
does not work until….
12-14 W gestation
Methergine (Methlyergonovine)
cannot be given via which route?
NEVER given IV
Methergine (Methlyergonovine)
drug class/substance type
Semisynthetic ergot alkaloid
Methergine (Methlyergonovine)
MoA
directly: acts on smooth muscle
-increases uterine motor activity
-increase tone, rate, and amplitude of contraction
Methergine (Methlyergonovine)
CV effects
alpha stimulation: Arterial vasoconstriction
inhibits endothelial derived relaxation factor release
Methergine (Methlyergonovine)
Contraindications
severe HTN
Preg induced HTN (PIH) (>140/90)
cardiac disease
Methergine (Methlyergonovine)
dose
0.2 mg IM every 2-4 hours (max 5 doses)
Methergine (Methlyergonovine)
onset and duration
onset: 2-5 min
duration: about 3 hours
Hemabate (Carboprost)
identity
Synthetic analogue of prostaglandin F2
Hemabate (Carboprost)
MoA
stimulates uterine contraction
increase of myometrial calcium
stimulates smooth muscle of GI tract to cause diarrhea
Hemabate (Carboprost)
effect on temperature
Increase in temperature possibly due to effect on hypothalamic thermoregulation
(can increase 2 degrees)
Hemabate (Carboprost)
contraindications
Airway constriction and wheezing
increase CO, BP and PVR (constriction of vascular smooth muscle)
Hemabate (Carboprost)
dose
onset
duration
Dose: 250 mcq IM repeated every 15-45 min (max 8 doses)
onset: immediate
duration: 2 hours
Misoprostol (Cytotec)
identity
Synthetic prostaglandin E1
Misoprostol (Cytotec)
uses
uterine atony
abortions
cervical ripening
peptic ulcer disease
Misoprostol (Cytotec)
dose
1-2 tablets buccal (200 mcq each)
rectally and vaginally (By OB)
Misoprostol (Cytotec)
onset & 1/2L
onset: rapid
half life: 20-40 min
Magnesium Sulfate (MgSO4)
uses
prevent eclamptic seizures (decrease incidence of seizure by 50 %)
stop premature labor (tocolytic)
Magnesium Sulfate (MgSO4)
MoA
-Inhibit ACh release at NMJ
-Mild vasodilator: decreases uterine activity = increase uterine blood
-dilates liver beds and kidneys to increase function
-decreases SVR
Magnesium Sulfate (MgSO4)
potentiates …….
nondepolarizers and depolarizers
(prob dont need to change dose tho)
T/F
Magnesium Sulfate (MgSO4) does not cross the placenta
False
neonate may show signs of respiratory depression, apnea and decreased tone
Magnesium Sulfate (MgSO4)
possible negative effects
(not including toxicity)
Can cause pulmonary edema
? correlation with chorioamnionitis
Magnesium Sulfate (MgSO4)
dose
4 grams over 20 min
drip: 2-3 grams/ hour
Magnesium Sulfate (MgSO4)
onset & duration
onset: immediate
duration: 20-30 min with good renal perfusion
Magnesium Sulfate (MgSO4)
must be assessing….
Deep Tendon Reflexes
Magnesium Toxicity Treatment
-Ca gluconate 1 gram over 2 min
-fluids
-diuresis
-O2
-Monitor mag levels
Magnesium Sulfate (MgSO4)
effect on uterus
Relaxes uterus a lot
caution w/ uterine atony/bleeding
Mag therapeutic levels
4-8
(my Mag & Mesh (CO2) are the same)
Mag level when we start to see resp depression
10
Labetalol in OB
few neonatal complications (bradycardia)
alpha & beta antagonist
rapid onset
Hydralazine in OB
MoA & side fx
decrease maternal BP & uterine vasc resistnce = increase Ut blood flow
Limiting side effects: maternal tachy<3 (SNS reflex to direct vasodilation), vomiting, tremors
Hydralazine in OB
vascular effects
potent vasodilator:
decrease afterload & PVR (esp if used w/ volume repletion)
Nipride
indication
acute hypertensive crisis
applies to OB & everybody
Nipride
vasc fx
potent arteriolar dilator
rapid onset and short duration
Nipride in OB
concern for maternal/fetal cyanide toxicity
unlikely if low doses 5-10 mcg/kg/min
T/F
Nipride is long-acting
False
rapid onset and short duration
Nitroglycerin (NTG)
MoA
may cause….
venodilator
decrease cardiac filling pressures by acting on capacitance vessels
may get reflex tachycardia
Volume Repletion (decrease ECF) in OB
uses
for severe pre-eclampsia to improve low CO
R & L filling pressures normalize:
-CI improves
-decrease mom’s HR & SVR decrease
-fetal circulation improves
Volume Repletion (decrease ECF) in OB
how it works
severe preeclampsia = low CO
must replenish intravasc. vol
R & L filling pressures normalize:
-CI improves
-decrease mom’s HR & SVR decrease
-fetal circulation improves
Volume Repletion (decrease ECF) + hydralazine
decreased peripheral resistance
(hydralazine = potent vasodilator, decreases afterload)
Ephedrine vs Neo in OB
Neosynephrine is the pressor of choice in OB
maintains fetal pH
ephedrine: wont decrease Ut bld flow but fetal tachy<3 & acidosis
both can treat hypoTN d/t regionals